ON THE CONTACT THEORY OE VOLTAIC ACTION. 
23 
Date. 
The following— 
Has to the following— 
At— 
A contact 
difference 
of 
potentials, 
in volts. 
/Remarks. 
°c. 
30/1/78 . 
Zinc sulphate, sp. gr. IT25, 
Copper sulphate, sp. gr. 
16-6 
+ 0-090 
Each of the numbers in the 
at 16--9 C. 
1-087, at 16°-6 C. 
preceding column is the 
Copper. 
17 
+ 0-103 
average of about ten obser- 
Zinc. 
Zinc sulphate, sp. gr. 1T25, 
17 
-0-238 
vations. 
at 16°-9 C. 
8/2/78 . 
Copper. 
Distilled water. 
+ 0-269 
11/2/78 . 
Zinc. 
13-5 
+ 0-088 
Zinc sulphate, saturated at 
13-5 
+ 0-120 
15° 3 C. 
Zinc. 
13-5 
+ 0-156 
Copper. 
16 
+ 0-100 
12/2/78 . 
Copper sulphate, saturated 
13 
+ 0-044 
The contact difference of 
10 A.M. 
at 15° C. 
potentials of saturated 
Zinc sulphate, saturated at 
14-5 
+ 0-190 
copper sulphate with dis- 
15°-3 C. 
tilled water was here mea- 
11 A.M. . 
Copper sulphate, saturated 
14-6 
+ 0-052 
sured several times on 
at 15° C. 
different occasions, as a 
3.15 P.M. 
16 
+ 0-040 
test of the efficiency of 
7.35 p.m. 
tt ft 
15 
+ 0-040 
our method of measuring 
15/2/78 . 
Copper sulphate, saturated 
16 
+ 0 041 
the difference of potentials 
at 15° C. 
of two liquids in contact. 
18/2/78 . 
Zinc sulphate, saturated at 
Copper sulphate, saturated 
14 
+ 0-090 
The comparative con- 
15°-3 C. 
at 15° C. 
stancy of the numbers 
Distilled water. 
15-5 
+ 0-184 
obtained on the different 
19/2/78 . 
Copper. 
Copper sulphate, saturated 
15-6 
+ 0-070 
occasions, 0-044, 0"052, 
at 15° C. 
0-040, 0-040, 0-041 volt 
tt . 
Distilled water. 
16 
+ 0-150 
(each being the mean of 
Zinc. 
17-4 
-0-105 
some ten observations), 
„ . 
Zinc sulphate, saturated at 
17 
-0-457 
proves that our method is 
17° C. 
practically accurate. 
Copper. 
Tin. 
17 
-0-456 
19/2/78 . 
Lead. 
18 
-0-542 
Lead. 
Zinc. 
18-7 
-0-210 
Zinc. 
Tin. 
19 
+ 0-281 
Copper . 
Iron. 
18 
-0-146 
20/2/78 . 
Lead. 
Tin. 
17-8 
+ 0-099 
21/2/78 . 
Iron. 
Water. 
13 
+ 0148 
Platinum. 
14 
+ 0-310 
Nitric acid. 
17 
+ 0-672 
Difficult to measure in con- 
Zinc. 
Distilled water with a slight 
17 
-0-241 
sequence of the film which 
trace of sulphuric acid. 
condensed on the gilt in- 
,, . 
Distilled water with about 
18 
-0-289 
duction plates. 
\ per cent, of sulphuric 
acid. 
,, . 
Distilled water with about 
19 
-0-312 
-3 per cent, of sulphuric 
acid. 
„ . 
1 of sulphuric acid and 20 
18-8 
-0-344 
The value slowly increased 
of distilled water by 
from the formation of a 
weight. 
salt on the surface of the 
zinc. 
» . 
1 of sulphuric acid and 30 
19 
-0-344 
The zinc slowly blackened, 
of distilled water by 
but not so quickly as 
weight. 
before. 
22/2/78 . 
tt .* * 
Solution sea-salt, sp.gr. P18, 
19 
-0-506 
at 20°-5 C. 
23/2/78 . 
Copper. 
15 
-0-475 
25/2/78 . 
Lead. 
Distilled water. 
17 
+ 0-184 
') . 
Strong sulphuric acid. . . 
17-8 
+ 0-720 
26/2/78 . 
Zinc. 
Sal-ammoniac, saturated at 
14 
-0-637 
15°*5 C. 
Copper. 
ft ft 
Strong sulphuric acid. . . 
15 
-0-396 
ft . 
17 
+ 1-056 
Lead. 
18 
+ 0-720 
Platinum. 
18 
+ 1-424 
ft . 
Lead. 
18 
-0-771 
27/2/78 . 
Copper. 
Platinum. 
15 
+ 0-238 
Platinum. 
Zinc. 
164 
-0-981 
J> . 
Iron. 
17 
-0-369 
ft . 
Tin. 
17 
-0-690 
